1. Field of the Invention
The present invention relates to communications control apparatus and method for a mobile body such as an automotive vehicle which communicate with another communication party via an electromagnetic wave.
2. Description of the Related Art
A communication countermeasure in a previously proposed vehicular communications control apparatus at an interval in which an electromagnetic wave environment is not favorable is exemplified by a Japanese Patent Application First Publication No. Heisei 5-199167 published on Aug. 6, 1993. In a car phone disclosed in this Japanese Patent Application Publication, a received level state obtained when the vehicle has traveled is stored in connection with the interval of an electromagnetic wave environment map and this electromagnetic wave state map information is displayed in a telephone call state. Thus, a vehicular driver can select a traveling route at which a favorable electromagnetic wave received state can be obtained.
Communication tools which perform wireless communications between the vehicle and another communication party include, in addition to the car phone, a recent communications device which transmits and receives a content of a, so-called, stream type in which downloaded data such as music, news, weather forecast, and internet radio are once buffered (stored in a buffer) and the information is continued to be play-backed.
When the above-described communications device disclosed in the above-described Japanese Patent Application First Publication is mounted in the vehicle disclosed in the above-described Japanese Patent Application Publication, the vehicle travels while selecting the interval of the traveling route in which the electromagnetic wave environment is favorable. However, according to a traveling situation, the vehicle is often needed to travel in the interval thereof in which the electromagnetic wave environment is not favorable. In this case, even if the stream type content is tried to be downloaded, the download is often interrupted at the interval in which the electromagnetic wave environment is not favorable.
It is, therefore, an object of the present invention to provide communications control apparatus and method which can predict a quantity required for a play-back of a data at an interval of a traveling scheduled route at which the electromagnetic wave environment is bad and at which the download of the content is not possible, can previously reserve the corresponding data quantity at another interval before the vehicle reaches to the above-described interval, at the other interval the electromagnetic wave environment being favorable, and can play-back the stream-type content without interruption even if the vehicle is passing through the above-described interval at which the electromagnetic wave environment is bad.
According to one aspect of the present invention, there is provided a communications control apparatus for an automotive vehicle, comprising: a road map storing section that stores a road map data; an electromagnetic wave environmental data storing section that stores an electromagnetic wave environmental data; a vehicular position retrieving section that retrieves a position of the vehicle; a traveling time predicting section that predicts a traveling time for which the vehicle travels on a traveling scheduled route using the road map data; a communication speed predicting section that predicts a communication speed when the vehicle travels on the traveling scheduled route using the electromagnetic wave environmental data; a playback speed retrieving section that retrieves a playback speed of a requested content; a buffer enabling quantity calculating section that calculates a buffer enabling quantity by which data of the requested content is enabled to be buffered into a receiving buffer during a vehicular run on the traveling scheduled route using the traveling time obtained from the traveling time predicting section and the communication speed obtained from the communication speed predicting section; and a receiving buffer setting section that sets a capacity of the receiving buffer according to a calculated result of the buffer enabling quantity calculating section and an upper limit value of the receiving buffer capacity the data of the requested content being downloaded onto the receiving buffer whose capacity is set by the receiving buffer setting section.
According to another aspect of the present invention, there is provided a communications control method for an automotive vehicle, comprising: storing a road map data; storing an electromagnetic wave environmental data; retrieving a position of the vehicle; predicting a traveling time for which the vehicle travels on a traveling scheduled route using the road map data; predicting a communication speed when the vehicle travels on the traveling scheduled route using the electromagnetic wave environmental data; retrieving a playback speed of a requested content; calculating a buffer enabling quantity by which data of the requested content is enabled to be buffered into a receiving buffer during a vehicular run on the traveling scheduled route using the traveling time obtained during the traveling time predicting and the communication speed obtained during the communication speed predicting; and setting a capacity of the receiving buffer according to a calculated result of the buffer enabling quantity calculating section and an upper limit value of the receiving buffer capacity, the data of the requested content being downloaded onto the capacity set receiving buffer.
This summary of the invention does not necessarily describe all necessary features so that the invention may also be a sub-combination of these described features.